Tobacco sheet, tobacco rod and smoking article

ABSTRACT

A tobacco sheet containing 15-60 mass % of a tobacco ingredient and 20-70 mass % of cellulose fibers, and having a thickness of 55-85 μm, a basis weight of 25-42 g/m 2 , and a tensile strength of 12 N/15 mm or more.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of PCT Application No. PCT/JP2019/022794, filed Jun. 7, 2019, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a tobacco sheet containing a tobacco material.

2. Description of the Related Art

There is a disclosure pertaining to a tobacco web containing a tobacco material (International Publication No. 96/32854). This tobacco web is intended to enclose a tobacco filler in a cylindrical shape. The tobacco web contains at least twice as much tobacco material as the base web in basis weight. The tobacco web is also called a “tobacco sheet”.

BRIEF SUMMARY OF THE INVENTION

A tobacco web of this type contains the tobacco material as a within-sheet component, and as such, the tobacco web has a lower tensile strength than the cigarette paper for conventional traditional cigarettes. Thus, the tobacco web, when used with a conventional cigarette making machine, could easily be torn during manufacture.

Also, the tobacco web has poor compatibility with glue adhesion. Due to this, a tobacco rod wrapped with such a tobacco web could suffer from an adhesion failure during manufacture, that is, the tobacco rod could easily trigger a rupture called a “punctured wrap”. Use of additional glue for improving the adhesion could lead to the protrusion of excess glue and degrade the appearance. An increase in the heater temperature within the cigarette making machine for improving the adhesion could burn the tobacco web and easily result in degraded appearance. Further, while it may be possible to allocate a sufficiently lengthy amount of time for the glue to cure and thereby improve adhesion, this would reduce the operating speed of the cigarette making machine and decrease manufacturing efficiency.

The object of the present invention includes providing a tobacco sheet that can be directly used with existing cigarette making machines and that allows for the fast manufacture of smoking articles through use of such.

A tobacco sheet according to an embodiment of the present invention contains a tobacco material in an amount of 10 to 60% by mass and cellulose fiber in an amount of 20 to 70% by mass, and having a thickness of 55 to 85 μm, a basis weight of 25 to 42 g/m², and a tensile strength of 12 N/15 mm or higher.

According to the present invention, it is possible to provide a tobacco sheet that can be directly used with existing cigarette making machines and that allows for the fast manufacture of smoking articles through use of such.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a schematic sectional view showing a little cigar according to an embodiment.

FIG. 2 is an exploded perspective view of the little cigar shown in FIG. 1 and shows its tipping paper, filter wrapping paper of a filter portion, and cigarette paper of a tobacco rod in their unfolded conditions.

FIG. 3 is a graph showing a relationship between Clark stiffness and thermal efficiency, obtained for cigarette papers of Examples 1 and 2, Comparative Examples 1 and 2, and a Reference Example.

FIG. 4 is a graph showing a relationship between Bekk smoothness and thermal efficiency, obtained for the cigarette papers of Examples 1 and 2, Comparative Examples 1 and 2, and the Reference Example.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of a smoking article, i.e., a little cigar, that contains a tobacco sheet as a cigarette paper will be described with reference to FIGS. 1 to 4. The description is intended to illustrate but not limit the present invention. Also, the figures show each element of the invention in a schematic manner. As such, dimensions read from the figures may not necessarily conform to the dimensions of actual products.

A little cigar 11 is a type of cigar that has substantially the same appearance and structure as a normal cigarette. The little cigar 11 differs from a cigarette merely in the aspect of using a tobacco sheet in place of a cigarette paper for the wrapping of a tobacco filler. The little cigar 11 includes a tobacco rod 12, a filter portion 13 provided adjacent to the tobacco rod 12, and a tipping paper 14 for connecting the tobacco rod 12 and the filter portion 13.

The filter portion 13 is cylindrical. The filter portion 13 includes a filter body 15, and a filter wrapping paper 16 covering the periphery of the filter body 15. The ends of the filter wrapping paper 16 overlap each other and are bonded together using, for example, an adhesive constituted by a vinyl acetate resin-based emulsion, etc.

The filter body 15 may be formed of various kinds of filler. In this embodiment, the filter body 15 is constituted by a filler of, for example, cellulose-based semisynthetic fiber such as cellulose acetate, but the filler is not limited thereto. Examples of the filler that may be used include plant fibers such as cotton, hemp, Manila hemp, palm, and rush, animal fibers such as wool and cashmere, cellulose-based regenerated fibers such as rayon, cellulose-based semisynthetic fibers such as cellulose diacetate and cellulose triacetate, synthetic fibers such as nylon, polyester, acrylic, polyethylene, and polypropylene, or any combination thereof. Besides the cellulose acetate filter described above, the constituent element of the filter portion 13 may be a charcoal filter containing charcoal particles or a filter containing particulates other than charcoal particles. Furthermore, the filter portion 13 may be composed of two or more segments.

The filter body 15 may contain a plasticizer. The plasticizer used in the filter body 15 of the filter portion 13 is not limited to any particular kind. For example, triethyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, dibutyl tartrate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, triacetin, triethyl phosphate, triphenyl phosphate, tripropionin, or any combination of these may be used as the plasticizer. In some cases, the plasticizer may be omitted.

The filter body 15 may contain a flavor such as menthol. The method of imparting the flavor is not limited to any particular method. For example, a string-type material that has adsorbed the flavor may be arranged inside the filter body 15. As another example, the filler of the filter portion 13 may contain the flavor. As a further example, a material such as a capsule in which the flavor is immobilized may be arranged inside the filter portion 13.

The type and materials of the filter wrapping paper 16 are not limited. The filter wrapping paper 16 may have air permeability as those adopted in general tobacco products, or have no air permeability. Typically, paper made of plant fiber is used as the material of the filter wrapping paper 16. In place of such paper, a sheet prepared by using chemical fiber of a polymer-based material (such as polypropylene, polyethylene, or nylon) or a sheet prepared by molding a melt of the polymer-based material may be used. As another option, metal foil such as aluminum foil may be used.

As the filter body 15, a non-wrap filter such as that disclosed in FIG. 15 of WO 2004/066761 may be used. The non-wrap filter has a filter material and an outer layer that places the filter material in a cylindrical shape, and this outer layer is obtained by thermoforming the filter material. Therefore, when the non-wrap filter is used, no filter wrapping paper is required.

The materials of the tipping paper 14 are not limited. As the tipping paper 14, paper (pulp) made of plant fiber is typically used. In place of such paper, a sheet prepared by using chemical fiber of a polymer-based material (such as polypropylene, polyethylene, or nylon) or a sheet prepared by molding a melt of the polymer-based material may be used. As another option, metal foil such as aluminum foil may be used.

The tobacco rod 12 includes a tobacco filler 17 and a cigarette paper 18 wound around the tobacco filler 17. The cigarette paper 18 has an overlap portion formed by its overlapping ends. In the overlap portion, the ends of the cigarette paper 18 are bonded together using, for example, an adhesive constituted by a vinyl acetate resin-based emulsion, etc.

The tobacco filler 17 is typically constituted by pieces obtained from leaf tobacco (i.e., dried tobacco leaves for use in tobacco products) cut in a prescribed length and width (that is, short fillers). The tobacco filler 17 may further contain crushed leaf tobacco shaped into a sheet and then cut into strips, namely, sheet-like pieces. The sheet-like pieces may be formed from a tobacco sheet 21 described later. The sheet-like pieces may contain an aerosol generating substrate and a flavor component. The aerosol generating substrate and the flavor component may also be added to the pieces of cut leaf tobacco. Examples of the aerosol generating substrate include glycerin, propylene glycol (PG), triethyl citrate (TEC), triacetin, 1,3-butanediol, etc. They may be used alone or in combination of two or more.

The cigarette paper 18 is constituted by paper containing a tobacco material, namely, the tobacco sheet 21. The tobacco sheet 21 contains, in addition to the tobacco material, cellulose fibers. The tobacco sheet 21 is typically constituted by a sheet made by a general papermaking process, but may be a sheet made by a different method (e.g., a rolling method, a casting method, etc.).

The cellulose fibers are typically pulp, which may be, for example, one or more of wood pulp, non-wood pulp, and synthetic fiber pulp. Preferably, the cellulose fibers are wood pulp. Note that the cellulose fibers do not contain fibers derived from tobacco leaves. The tobacco sheet 21 may contain the cellulose fibers in an amount of 20 to 70% by mass, which is preferably an amount of 25 to 65% by mass, and more preferably an amount of 30 to 60% by mass.

The tobacco sheet 21 contains a tobacco material. The tobacco material generally refers to leaf tobacco that has been subjected to a drying operation and that is in a ready-to-use state for tobacco products or in a preparatory stage for such use, as well as to processed goods of such leaf tobacco. Preferably, the tobacco material is leaf tobacco (i.e., dried tobacco leaves for use in tobacco products). More preferably, the tobacco material is a fine or shredded raw material (i.e., fine or shredded leaf tobacco) obtained by micro-cutting or shredding leaf tobacco. The tobacco sheet 21 may contain the tobacco material in an amount of 10 to 60% by mass, which is preferably an amount of 15 to 55% by mass, and more preferably an amount of 20 to 50% by mass. An increase in the mass % of the tobacco material tends to lower the tensile strength and the Bekk smoothness.

The tobacco sheet 21 may further contain other additives such as a paper filler and a combustion aid. The tobacco sheet 21 contains such other additives preferably in an amount of 10 to 40% by mass, more preferably in an amount of 15 to 35% by mass, and even more preferably in an amount of 20 to 30% by mass. These additives may be any one of calcium carbonate, aluminum hydroxide, aluminum oxide, titanium dioxide, kaolin, talc, and silica, or a combination of any of these.

The tobacco sheet 21 may have a basis weight of 25 to 42 g/m², which is preferably 28 to 40 g/m², more preferably 30 to 39 g/m², and even more preferably 32 to 38 g/m².

The tobacco sheet 21 may have a thickness of 55 to 85 μm, which is preferably 60 to 80 μm, more preferably 65 to 78 μm, and even more preferably 69 to 76 μm.

It is preferable that the tobacco sheet 21 has been subjected to a calender processing. The calender processing includes having the object (that is, the tobacco sheet) pass through smooth rollers so that it will be endowed with smoothness and shine, and then compressed to a reduced and averaged thickness. Here, one of the rollers is an iron roller, and the other is an elastic roller constituted by an iron roller around which an elastic material such as paper, cotton, rubber, etc. is wound.

The tobacco sheet 21 may have a tensile strength of 12 N/15 mm or higher, which is preferably 12 to 30 N/15 mm, more preferably 13 to 20 N/15 mm, and even more preferably 13 to 15 N/15 mm. The measurement for tensile strength followed JIS P8113:2006. The actual tensile strength measurement adopted “Tensile Strength Tester (Strograph E-S)” manufactured by Toyo Seiki Seisaku-sho, Ltd.

The tobacco sheet 21 may have a Clark stiffness of 15 cm³/100 or lower, which is preferably 10 to 15 cm³/100, more preferably 11 to 14 cm³/100, and even more preferably 12 to 13 cm³/100. The measurement for Clark stiffness followed JIS P8143:2009. The actual Clark stiffness measurement adopted “Clark Stiffness Tester” manufactured by Toyo Seiki Seisaku-sho, Ltd. Note that lowering the Clark stiffness will reduce the force acting in the peeling direction (repulsive force) at bonding. Consequently, this will cut down the time required to dry the adhesive, and speed up the wrapping for the tobacco rod 12. More concretely, improvement in the wrapping speed has been confirmed not only in the manufacture of a tobacco rod having a circumference of 23 to 27 mm (a so-called “normal” size), but also in the manufacture of a tobacco rod having a circumference of 16 to 23 mm (a so-called “thin” size) which includes a tobacco rod having a circumference of 18 to 23 mm (a so-called “slim” size) and a tobacco rod having a circumferences of 16 to 18 mm (a so-called “super slim” size).

The tobacco sheet 21 may have a Bekk smoothness of 15 sec or higher, which is preferably 15 to 30 sec, more preferably 17 to 27 sec, and even more preferably 19 to 24 sec. The measurement for Bekk smoothness followed JIS P8119:1998. The actual Bekk smoothness measurement adopted “Digi-Bekk Smoothness Tester” manufactured by Toyo Seiki Seisaku-sho, Ltd. Note that a greater Bekk smoothness value is indicative of a subject surface having a higher smoothness. Increasing the Bekk smoothness will improve the coating condition and the bonding strength of the adhesive, which will consequently reduce the time required to dry the adhesive and speed up the wrapping for the tobacco rod 12.

Next, a description will be given of a method for manufacturing the cigarette paper 18 (tobacco sheet 21) according to the embodiment, as well as a method for manufacturing a smoking article that uses this cigarette paper 18.

The cigarette paper 18 (tobacco sheet 21) according to the embodiment may be manufactured by a widely known papermaking process with a partial modification.

The papermaking process for manufacturing the cigarette paper 18 (tobacco sheet 21) according to the embodiment includes four steps as in the known papermaking process, which are (1) a pulping step, (2) a stock preparing step, (3) a papermaking step, and (4) a shaping and finishing step.

(1) The pulping step includes chemical and mechanical processing. This process takes out cellulose fibers, in other words, pulp, from wood materials. The pulp is subjected to dust contaminant removal and then dehydrated and bleached.

(2) The stock preparing step includes two steps, namely, defibration by a pulper and a refining by a refiner. The defibrated pulp is mixed with water uniformly. To this water-pulp mixture, leaf tobacco, which has been cut into fine pieces by a separate step, is mixed in. The refiner cuts the pulp and the fine pieces of leaf tobacco into even shorter fibers and gives these fibers a fluffy texture (fibrillation) so they can be easily coupled with one another.

For the cigarette paper 18 (tobacco sheet 21) according to the embodiment, the further facilitation of fibrillation and enhanced coupling between the fibers can be achieved by increasing the degree of refining performed in the known papermaking process. It is possible to increase the degree of refining by, for example, performing the refining under conditions more demanding than those for the known papermaking process (e.g., adopting an increased concentration of the raw materials, or a lowered flow rate of the raw materials). As the fibrillation is facilitated and the coupling between the fibers is enhanced, the tobacco sheet can be equipped with increased strength and a reduced basis weight. The reduction in basis weight of the tobacco sheet will allow for the reduction in both thickness and stiffness.

(3) The papermaking step includes an operation in which the material fed from the stock preparing process is made into actual paper. In the wire section, a mixture of pulp, leaf tobacco, and water is evenly spread. In the press section, water is squeezed from the mixture. In the dryer section, tobacco sheet base paper obtained by the water removal is dried. In the calender section, the surface of the tobacco sheet base paper is smoothed. In the reel section, the produced tobacco sheet base paper is wound as a roll.

(4) The shaping and finishing step includes smoothening the surface of the tobacco sheet base paper using a calender device. The calender device includes a first roller made of iron and a second roller facing the first roller and having elasticity. The calender device is adapted to hold the tobacco sheet base paper between the first roller and the second roller and press the same so that a calendered tobacco sheet endowed with smoothness can be formed. The second roller is constituted by an iron roller around which an elastic material such as paper, cotton, rubber, etc. is wound so that it has an elastic surface. Upon performing the calender processing with the calender device, and other shaping and post-processing such as coating, cutting, and roll-forming as appropriate, the tobacco sheet 21 is complete.

This tobacco sheet 21 is fed into a conventional cigarette making machine, whereby the tobacco rod 12 is formed. The tobacco rod 12 is connected, using the tipping paper 14, to the filter portion 13 produced in a separate process, and a smoking article (that is, the little cigar 11) is thus complete.

The tobacco sheet 21 and the smoking article (i.e., the little cigar 11) using the tobacco sheet 21 are not limited to the foregoing embodiments or their modifications, and may be implemented with alterations to the constitution without departing from the gist of the embodiments. Also, one or more components may be omitted from the entire constitution illustrated through the embodiments.

EXAMPLES

Parameters of the cigarette papers used in Examples 1 and 2, Comparative Examples 1 and 2, and a Reference Example are shown in below Tables 1 to 3.

TABLE 1 Tobacco Cellulose Basis Type of cigarette material fiber Additive weight Thickness Calender paper (mass %) (mass %) (mass %) (g/m²) (μm) processing Reference General cigarette 0 70 30 26 45 None Example paper Comparative Tobacco sheet 70 10 20 46 106 None Example 1 Comparative Tobacco sheet 50 30 20 46 99 Done Example 2 Example 1 Tobacco sheet 50 30 20 38 76 Done Example 2 Tobacco sheet 20 60 20 32 69 Done

TABLE 2 Bekk Type of Tensile Clark smooth- cigarette strength stiffness ness paper (N/15 mm) (cm³/100) (sec) Reference General 14  9 48 Example cigarette paper Comparative Tobacco sheet 10 18  7 Example 1 Comparative Tobacco sheet 11 18 10 Example 2 Example 1 Tobacco sheet 15 12 19 Example 2 Tobacco sheet 13 13 24

TABLE 3 Wrapping Heater Thermal Quantitative ratio Type of cigarette speed temperature efficiency of adhesive Wrapping paper (cpm) (° C.) (%) (%) suitability Reference General 9,000 200 100%  100% No problem Example cigarette paper Comparative Tobacco sheet 2,000 280  6% 250% Punctured wrap Example 1 occurred Comparative Tobacco sheet 4,000 280 25% 125% Punctured wrap Example 2 occurred Example 1 Tobacco sheet 8,000 280 51% 125% No problem Example 2 Tobacco sheet 6,000 280 38% 125% No problem

Example 1

The little cigar 11 according to Example 1 adopted a cigarette paper constituted by the tobacco sheet 21 containing a tobacco material and cellulose fibers. This tobacco sheet 21 contained the tobacco material in an amount of 50% by mass and the wood pulp in an amount of 30% by mass. The tobacco sheet 21 contained other additives such as a paper filler and a combustion aid in an amount of 20% by mass. The tobacco sheet 21 had a basis weight of 38 g/m². The tobacco sheet 21 had a thickness of 76 μm. The tobacco sheet 21 in Example 1 was subjected to a calender processing.

The tobacco sheet 21 had a tensile strength of 15 N/15 mm. The tobacco sheet 21 had a Clark stiffness of 12 cm³/100. The tobacco sheet 21 had a Bekk smoothness of 19 sec.

Using the tobacco sheet 21 of such constitution, the tobacco rod 12 and the little cigar 11 were prepared. A cigarette making machine intended for use in the formation of general cigarettes was employed for the wrapping of the tobacco rod 12 and the manufacture of the little cigar 11 including this tobacco rod 12. The manufacture speed of the little cigar 11 was 8000 cpm. Here, “cpm” indicates the number of little cigars 11 manufactured per one minute. The tobacco sheet 21 was made to pass through the heater of the cigarette making machine at a speed of 456 m/min.

An adhesive constituted by a vinyl acetate resin-based emulsion was used as the adhesive for bonding together the ends of the tobacco sheet 21. The amount of the adhesive was set to 125% by mass, assuming that the mass used for bonding together the ends (overlap portion) of a “general cigarette paper” in the Reference Example is 100%. In Table 3, the amount of each adhesive is given as an adhesive's quantitative ratio (%) calculated by the following formula.

Quantitative ratio of adhesive (%)={(Mass of adhesive used for wrapping a subject little cigar)/(Mass of adhesive used for wrapping a cigarette according to the Reference Example)}×100

In the cigarette making machine, the heater temperature for drying the adhesive was set to 280° C. In this example, no problem was found with regards to wrapping suitability, and the tobacco rod 12 did not trigger any rupture due to adhesion failure, a so-called “punctured wrap”, during the wrapping. Neither did the heat for drying the adhesive burn the tobacco sheet 21.

A sensory assessment for the smoking taste of the little cigar 11 according to Example 1 was conducted, with the participation of several testers. As the outcome, tester comments comparing the little cigar 11 to the on-market little cigar “Golden Bat” (Japan Tobacco Inc.), were: “It feels a little fibrous, but miscellaneous taste has been reduced. Overall, flavor from the flavorant added to the tobacco is more easily detected and the tobacco taste is richer, while bitterness is reduced. The smoking taste falls within the range which assures validity as a product.” As such, the smoking taste of the little cigar 11 according to Example 1 was generally confirmed to be good.

Example 2

The little cigar 11 according to Example 2 adopted a cigarette paper constituted by the tobacco sheet 21 containing a tobacco material and cellulose fibers. This tobacco sheet 21 contained the tobacco material in an amount of 20% by mass and the wood pulp in an amount of 60% by mass. The tobacco sheet 21 contained other additives such as a paper filler and a combustion aid in an amount of 20% by mass. The tobacco sheet 21 had a basis weight of 32 g/m². The tobacco sheet 21 had a thickness of 69 μm. The tobacco sheet 21 in Example 2 was subjected to a calender processing.

The tobacco sheet 21 had a tensile strength of 13 N/15 mm. The tobacco sheet 21 had a Clark stiffness of 13 cm³/100. The tobacco sheet 21 had a Bekk smoothness of 24 sec.

Using the tobacco sheet 21 of such constitution, the tobacco rod 12 and the little cigar 11 were prepared. A general cigarette making machine was employed for the wrapping of the tobacco rod 12 and the manufacture of the little cigar 11 including this tobacco rod 12. The manufacture speed was 6000 cpm. The tobacco sheet 21 was made to pass through the heater of the cigarette making machine at a speed of 342 m/min.

An adhesive constituted by a vinyl acetate resin-based emulsion was used as the adhesive for bonding together the ends of the tobacco sheet 21. The amount of the adhesive was set to 125% by mass, assuming that the mass used for bonding together the ends (overlap portion) of a “general cigarette paper” in the Reference Example is 100%. In the cigarette making machine, the heater temperature for drying the adhesive was set to 280° C. In this example, no problem was found with regards to wrapping suitability, and the tobacco rod 12 did not trigger any rupture due to adhesion failure, a so-called “punctured wrap”, during the wrapping. Neither did the heat for drying the adhesive burn the tobacco sheet 21.

A sensory assessment for the smoking taste of the little cigar 11 according to Example 2 was conducted, with the participation of several testers. As the outcome, tester comments comparing the little cigar 11 to the on-market little cigar “Golden Bat” (Japan Tobacco Inc.), were: “Lingering sweetness in the aftertaste tends to increase. Strength, inhaling sensation, and bitterness have been further reduced (as compared to the little cigar according to Example 1), and the characteristics defining of a little cigar are weakened. The smoking taste falls within the acceptable range.” As such, the smoking taste of the little cigar 11 according to Example 2 was confirmed to be in the acceptable range for validity as a product.

Comparative Example 1

The little cigar 11 according to Comparative Example 1 adopted a cigarette paper constituted by the tobacco sheet 21 containing a tobacco material and cellulose fibers. This tobacco sheet 21 contained the tobacco material in an amount of 70% by mass and the wood pulp in an amount of 10% by mass. The tobacco sheet 21 contained other additives such as a paper filler and a combustion aid in an amount of 20% by mass. The tobacco sheet 21 had a basis weight of 46 g/m². The tobacco sheet 21 had a thickness of 106 μm. The tobacco sheet 21 in Comparative Example 1 was not subjected to a calender processing.

The tobacco sheet 21 had a tensile strength of 10 N/15 mm. The tobacco sheet 21 had a Clark stiffness of 18 cm³/100. The tobacco sheet 21 had a Bekk smoothness of 7 sec.

Using the tobacco sheet 21 of such constitution, the tobacco rod 12 and the little cigar 11 were prepared. A general cigarette making machine was employed for the wrapping of the tobacco rod 12 and the manufacture of the little cigar 11 including this tobacco rod 12. The manufacture speed was 2000 cpm. The tobacco sheet 21 was made to pass through the heater of the cigarette making machine at a speed of 114 m/min.

An adhesive constituted by a vinyl acetate resin-based emulsion was used as the adhesive for bonding together the ends of the tobacco sheet 21. The amount of the adhesive was set to 250% by mass, assuming that the mass used for bonding together the ends (overlap portion) of a “general cigarette paper” in the Reference Example is 100%. In the cigarette making machine, the heater temperature for drying the adhesive was set to 280° C. In this comparative example, the tobacco rod 12 caused a rupture due to adhesion failure, a so-called “punctured wrap”, during the wrapping. As such, the little cigar 11 according to Comparative Example 1 was confirmed to be problematic in terms of wrapping suitability. It is noted that the heat for drying the adhesive did not burn the tobacco sheet 21.

Comparative Example 2

The little cigar 11 according to Comparative Example 2 adopted a cigarette paper constituted by the tobacco sheet 21 containing a tobacco material and cellulose fibers. This tobacco sheet 21 contained the tobacco material in an amount of 50% by mass and the wood pulp in an amount of 30% by mass. The tobacco sheet 21 contained other additives such as a paper filler and a combustion aid in an amount of 20% by mass. The tobacco sheet 21 had a basis weight of 46 g/m². The tobacco sheet 21 had a thickness of 99 μm. The tobacco sheet 21 in Comparative Example 2 was subjected to a calender processing.

The tobacco sheet 21 had a tensile strength of 11 N/15 mm. The tobacco sheet 21 had a Clark stiffness of 18 cm³/100. The tobacco sheet 21 had a Bekk smoothness of 10 sec.

Using the tobacco sheet 21 of such constitution, the tobacco rod 12 and the little cigar 11 were prepared. A general cigarette making machine was employed for the wrapping of the tobacco rod 12 and the manufacture of the little cigar 11 including this tobacco rod 12. The manufacture speed was 4000 cpm. The tobacco sheet 21 was made to pass through the heater of the cigarette making machine at a speed of 228 m/min.

An adhesive constituted by a vinyl acetate resin-based emulsion was used as the adhesive for bonding together the ends of the tobacco sheet 21. The amount of the adhesive was set to 125% by mass, assuming that the mass used for bonding together the ends (overlap portion) of a “general cigarette paper” in the Reference Example is 100%. In the cigarette making machine, the heater temperature for drying the adhesive was set to 280° C. In this comparative example, the tobacco rod 12 caused a rupture due to adhesion failure, a so-called “punctured wrap”, during the wrapping. As such, the little cigar 11 according to Comparative Example 2 was confirmed to be problematic in terms of wrapping suitability. It is noted that the heat for drying the adhesive did not burn the tobacco sheet 21.

Reference Example

The smoking article according to the Reference Example adopted a “general cigarette paper” which did not contain a tobacco material and was composed mainly of cellulose fibers. As such, the smoking article according to the Reference Example was a cigarette rather than a little cigar. This cigarette paper contained wood pulp in an amount of 70% by mass. The cigarette paper contained other additives such as a paper filler and a combustion aid in an amount of 30% by mass. The cigarette paper had a basis weight of 26 g/m². The cigarette paper had a thickness of 45 μm. The cigarette paper in the Reference Example was not subjected to a calender processing.

The “general cigarette paper” had a tensile strength of 14 N/15 mm. The cigarette paper had a Clark stiffness of 9 cm³/100. The cigarette paper had a Bekk smoothness of 48 sec.

Using the “general cigarette paper” as above, the tobacco rod 12 and the cigarette were prepared. A general cigarette making machine was employed for the wrapping of the tobacco rod 12 and the manufacture of the cigarette including this tobacco rod 12. The manufacture speed was 9000 cpm. The cigarette paper was made to pass through the heater of the cigarette making machine at a speed of 513 m/min.

An adhesive constituted by a vinyl acetate resin-based emulsion was used as the adhesive for bonding together the ends of the “general cigarette paper”. The amount of the adhesive here was 100% by mass, as the mass for bonding together the ends (overlap portion) of this “general cigarette paper” was the baseline 100%. In the cigarette making machine, the heater temperature for drying the adhesive was set to 200° C. Each condition in this Reference Example was a proven condition used for the wrapping of general cigarettes, and naturally, no problem was found in terms of wrapping suitability. Thus, the tobacco rod did not trigger any rupture due to adhesion failure, a so-called “punctured wrap”, during the wrapping. The heat for drying the adhesive did not burn the tobacco sheet 21.

[Evaluation for the Relationship Between Clark Stiffness and Thermal Efficiency]

First, “quantity of drying heat” was defined as follows.

Quantity of drying heat=Heater temperature (° C.)/Speed of cigarette paper passing through the heater (m/min)

Next, “thermal efficiency (%)” was defined as follows.

Thermal efficiency (%)=[{(Quantity of drying heat for a cigarette according to the Reference Example)/(Quantity of drying heat for a subject little cigar)}/(Quantitative ratio of adhesive)]×100

The “quantitative ratio of adhesive” was as defined above.

Quantitative ratio of adhesive (%)={(Mass of adhesive used for wrapping a subject little cigar)/(Mass of adhesive used for wrapping a cigarette according to the Reference Example)}×100

Here, FIG. 3 shows the relationship between Clark stiffness and thermal efficiency, obtained for each of Examples 1 and 2, Comparative Examples 1 and 2, and the Reference Example. It has been confirmed that a lower Clark stiffness gives a higher thermal efficiency. This is considered to be attributable to the mechanism that the lowering of the cigarette paper stiffness (Clark stiffness) reduces the force acting in the peeling direction (repulsive force) at bonding, consequently reducing the time required to dry the adhesive and speeding up the wrapping for the tobacco rod.

The following can be derived from this evaluation. If, as in the tobacco sheets of Examples 1 and 2, the Clark stiffness can be reduced below those in Comparative Examples 1 and 2, the efficiency of manufacturing little cigars will improve.

[Evaluation for the Relationship Between Bekk Smoothness and Thermal Efficiency]

FIG. 4 shows the relationship between Bekk smoothness and thermal efficiency, obtained for each of Examples 1 and 2, Comparative Examples 1 and 2, and the Reference Example. It has been confirmed that a higher Bekk smoothness gives a higher thermal efficiency. This is considered to be attributable to the mechanism that smoothening the cigarette paper improves the coating condition and the bonding strength of the adhesive, consequently reducing the time required to dry the adhesive and speeding up the wrapping for the tobacco rod.

The following can be derived from this evaluation. If, as in the tobacco sheets of Examples 1 and 2, the Bekk smoothness can be raised above those in Comparative Examples 1 and 2, the efficiency of manufacturing little cigars will improve.

The foregoing embodiments and also the examples, the comparative examples, and the reference example lead to the following observations.

According to an embodiment, the tobacco sheet 21 contains a tobacco material in an amount of 10 to 60% by mass and cellulose fibers in an amount of 20 to 70% by mass, and has a thickness of 55 to 85 μm, a basis weight of 25 to 42 g/m², and a tensile strength of 12 N/15 mm or higher. With this constitution, the tobacco sheet 21 can maintain its tensile strength at a level that is to some extent high, even when it is formed to contain a given amount of tobacco material with respect to the cellulose fibers. Therefore, it is also possible for the tobacco sheet 21 to be used in lieu of the component member serving as a support structure, for example, the cigarette paper 18 wound around the tobacco filler 17, the filter wrapping paper 16 covering the periphery of the filter body 15, or the tipping paper 14 connecting the tobacco rod 12 and the filter portion 13. As another option, the tobacco sheet 21 can also be used as the tobacco filler 17 having a hard-to-collapse characteristic.

According to a preferred embodiment, the tobacco sheet 21 in the foregoing embodiment has a Clark stiffness of 15 cm³/100 or lower. With this constitution, the tobacco sheet 21 can have a Clark stiffness reduced and approximated to that of general cigarette paper. Thus, when the tobacco sheet 21 is used as each of the wrappers discussed above (namely, the cigarette paper 18, the filter wrapping paper 16, and the tipping paper 14), the shape of the cylindrical structure (that is, the tobacco rod 12, the filter portion 13, and the little cigar 11 or the cigarette) wound by the same can be stabilized. This can prevent, to the maximum extent, the respective cylindrical structures from triggering adhesion failure and also a resulting rupture.

According to a preferred embodiment, the tobacco sheet 21 in any of the foregoing embodiments has a Bekk smoothness of 15 sec or higher. With this constitution, the tobacco sheet 21 can have a Bekk smoothness increased and approximated to that of general cigarette papers. Thus, when the tobacco sheet 21 is used as each of the wrappers discussed above (namely, the cigarette paper 18, the filter wrapping paper 16, and the tipping paper 14), the increased smoothness of the tobacco sheet 21 can improve the coating condition and the bonding strength of the adhesive applied at the overlap portion between its ends. Accordingly, the shape of the cylindrical structure (that is, the tobacco rod 12, the filter portion 13, and the little cigar 11 or the cigarette) wound by the corresponding wrapper can be stabilized. This can consequently prevent, to the maximum extent, the respective cylindrical structures from triggering adhesion failure and also a resulting rupture.

According to a preferred embodiment, the tobacco sheet 21 in any of the foregoing embodiments is subjected to a calender processing. With this constitution, the calendered tobacco sheet 21 can have a reduced thickness and a reduced Clark stiffness. Further, the calender processing can increase the Bekk smoothness. Thus, for example, when the tobacco sheet 21 is used as each of the wrappers discussed above (namely, the cigarette paper 18, the filter wrapping paper 16, and the tipping paper 14), the coating condition and the bonding strength of the adhesive applied at the overlap portion between the ends of the tobacco sheet 21 can be improved. Accordingly, the shape of the formed cylindrical structure (that is, the tobacco rod 12, the filter portion 13, and the little cigar 11 or the cigarette) can be stabilized.

According to a preferred embodiment, the tobacco sheet 21 in any of the foregoing embodiments is a sheet made by a papermaking process. In this case, since the tobacco sheet 21 can be made through the general papermaking process, the existing papermaking machine for use in the manufacture of cigarette paper 18 for traditional cigarettes can also be directly employed in the manufacture of the tobacco sheet 21. Accordingly, installing a papermaking machine for the manufacture of the tobacco sheet 21 is not required, thus allowing for the reduction in the costs for manufacturing the tobacco sheet 21.

According to a preferred embodiment, the tobacco sheet 21 in any of the foregoing embodiments is a cigarette paper to be wound around the tobacco filler 17. In this case, since the tensile strength of the tobacco sheet 21 can be made sufficiently high, a rupture in the tobacco sheet 21 can also be prevented when it is used as the cigarette paper 18.

As in the foregoing description, the use of the above tobacco sheet enabled the manufacture of a cylindrical structure as wide as a normal cigarette (i.e., a circumference of about 25 mm) without causing a punctured wrap, and also the manufacture of a cylindrical structure slimmer than a normal cigarette without causing a punctured wrap. In particular, the manufacture of a cylindrical structure having a circumference of about 17 mm, a so-called “super slim” size, was also successful. That is, use of the above tobacco sheet renders it possible to manufacture smoking articles having a circumference of 16 to 27 mm without causing a punctured wrap. Especially with a Clark stiffness of 15 cm³/100 or lower, the tobacco sheet was not apt to display repulsive behavior at the time of wrapping, and the manufacture of slim cylindrical structures was facilitated.

From the foregoing, the above tobacco sheet, by being applied to the existing cigarette making machine, can realize the fast manufacture of smoking articles. Note that the fast manufacture here refers to, for example, 5000 cpm or higher.

Other embodiments of the present invention will be set forth.

[1] A tobacco sheet containing a tobacco material in an amount of 10 to 60% by mass and cellulose fiber in an amount of 20 to 70% by mass, and having a thickness of 55 to 85 μm, a basis weight of 25 to 42 g/m², and a tensile strength of 12 N/15 mm or higher.

[2] The tobacco sheet according to [1], wherein the tensile strength is 12 to 30 N/15 mm, which is preferably 13 to 20 N/15 mm, and more preferably 13 to 15 N/15 mm.

[3] The tobacco sheet according to [1] or [2], having a Clark stiffness of 15 cm³/100 or lower, which is preferably 10 to 15 cm³/100, more preferably 11 to 14 cm³/100, and even more preferably 12 to 13 cm³/100.

[4] The tobacco sheet according to any one of [1] to [3], having a Bekk smoothness of 15 sec or higher, which is preferably 15 to 30 sec, more preferably 17 to 27 sec, and even more preferably 19 to 24 sec.

[5] The tobacco sheet according to any one of [1] to [4], wherein the cellulose fiber is contained in an amount of 25 to 65% by mass, which is preferably an amount of 30 to 60% by mass.

[6] The tobacco sheet according to any one of [1] to [5], wherein the cellulose fiber do not contain fiber derived from tobacco leaves.

[7] The tobacco sheet according to any one of [1] to [6], wherein the cellulose fiber is pulp, which is preferably one or more selected from the group consisting of wood pulp, non-wood pulp, and synthetic fiber pulp.

[8] The tobacco sheet according to any one of [1] to [7], wherein the cellulose fiber is wood pulp.

[9] The tobacco sheet according to any one of [1] to [8], wherein the tobacco material is contained in an amount of 15 to 55% by mass, which is preferably an amount of 20 to 50% by mass.

[10] The tobacco sheet according to any one of [1] to [9], wherein the tobacco material is leaf tobacco.

[11] The tobacco sheet according to any one of [1] to [10], further containing an additive preferably in an amount of 10 to 40% by mass, more preferably in an amount of 15 to 35% by mass, and even more preferably in an amount of 20 to 30% by mass.

[12] The tobacco sheet according to any one of [1] to [11], wherein the additive is one or more selected from the group consisting of calcium carbonate, aluminum hydroxide, aluminum oxide, titanium dioxide, kaolin, talc, and silica.

[13] The tobacco sheet according to any one of [1] to [12], wherein the basis weight is 28 to 40 g/m², which is preferably 30 to 39 g/m², and more preferably 32 to 38 g/m². [14] The tobacco sheet according to any one of [1] to [13], wherein the thickness is 60 to 80 μm, which is preferably 65 to 78 μm, and more preferably 69 to 76 μm.

[15] The tobacco sheet according to any one of [1] to [14], which is subjected to a calender processing. [16] The tobacco sheet according to any one of [1] to [15], which is for use as a cigarette paper.

[17] A tobacco rod comprising:

a tobacco filler; and

the tobacco sheet according to any one of [1] to [16] which is a cigarette paper wound around the tobacco filler.

[18] A smoking article comprising:

a tobacco rod comprising a tobacco filler, and the tobacco sheet according to any one of [1] to [16] which is a cigarette paper wound around the tobacco filler; and

a filter portion provided facing the tobacco rod.

[19] The smoking article according to [18], having a circumference of 16 to 27 mm.

[20] The smoking article according to [18], having a circumference of 23 to 27 mm.

[21] The smoking article according to [18], having a circumference of 16 to 23 mm.

[22] The smoking article according to [18], having a circumference of 18 to 23 mm.

[23] The smoking article according to [18], having a circumference of 16 to 18 mm.

REFERENCE SIGNS LIST

11 . . . Little cigar, 12 . . . Tobacco rod, 13 . . . Filter portion, 14 . . . Tipping paper, 15 . . . Filter body, 16 . . . Filter wrapping paper, 17 . . . Tobacco filler, 18 . . . Cigarette paper, 21 . . . Tobacco sheet. 

1. A tobacco sheet containing a tobacco material in an amount of 10 to 60% by mass and cellulose fiber in an amount of 20 to 70% by mass, and having a thickness of 55 to 85 μm, a basis weight of 25 to 42 g/m², and a tensile strength of 12 N/15 mm or higher.
 2. The tobacco sheet according to claim 1, having a Clark stiffness of 15 cm³/100 or lower.
 3. The tobacco sheet according to claim 1, having a Bekk smoothness of 15 sec or higher.
 4. The tobacco sheet according to claim 1, which is subjected to a calender processing.
 5. The tobacco sheet according to claim 1, which is a sheet made by a papermaking process.
 6. The tobacco sheet according to claim 1, which is a cigarette paper to be wound around a tobacco filler.
 7. A tobacco rod comprising: a tobacco filler; and a tobacco sheet which is a cigarette paper wound around the tobacco filler, wherein the tobacco sheet contains a tobacco material in an amount of 15 to 60% by mass and cellulose fiber in an amount of 20 to 70% by mass, and has a thickness of 55 to 85 μm, a basis weight of 25 to 42 g/m², and a tensile strength of 12 N/15 mm or higher.
 8. A smoking article comprising: a tobacco rod comprising a tobacco filler, and a tobacco sheet which is a cigarette paper wound around the tobacco filler; and a filter portion provided facing the tobacco rod, wherein the tobacco sheet contains a tobacco material in an amount of 15 to 60% by mass and cellulose fiber in an amount of 20 to 70% by mass, and has a thickness of 55 to 85 μm, a basis weight of 25 to 42 g/m², and a tensile strength of 12 N/15 mm or higher.
 9. The smoking article according to claim 8, having a circumference of 16 to 27 mm. 